rpc: reduce LOCK(cs_main) scope in gettxoutproof

src/rpc/txoutproof.cpp

@@ -84,13 +84,13 @@ static RPCHelpMan gettxoutproof()
                 g_txindex->BlockUntilSyncedToCurrentChain();
             }
 
-            LOCK(cs_main);
-
             if (pblockindex == nullptr) {
                 const CTransactionRef tx = GetTransaction(/*block_index=*/nullptr, /*mempool=*/nullptr, *setTxids.begin(), chainman.GetConsensus(), hashBlock);
                 if (!tx || hashBlock.IsNull()) {
                     throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not yet in block");
                 }
+
+                LOCK(cs_main);
                 pblockindex = chainman.m_blockman.LookupBlockIndex(hashBlock);
                 if (!pblockindex) {
                     throw JSONRPCError(RPC_INTERNAL_ERROR, "Transaction index corrupt");